The present invention relates to a multi-layer data storage medium, for example, an optical disk and so on, and a recording layer identification method of identifying a recording layer of the multi-layer data storage medium.
In a case where data is stored in a recording layer of a multi-layer data storage medium, and in a case where data in a recording layer of a multi-layer data storage medium is reproduced or deleted, after recognizing a recording layer on which light is condensed at that time, scanning of an objective recording layer by an object lens and identifying the recording layer on which scanning is performed, recording, reproducing and deleting operations are performed.
In order to identify the recording layer on which scanning is performed, methods of obtaining data of the recording layer information from a wobble signal and from a difference of a reproducing signal amplitude, by traditionally using a difference of a spiral of a guide groove, are known.
Japanese patent publication number 2002-117591 discloses a method of confirming a position of a recording layer by using differences of a depth, a width, an amplitude and a cycle of a spiral, of a guide groove.
Japanese patent publication number 2006-309860 discloses a method of confirming the position of the recording layer by using a difference of an amplitude of a reproducing signal.
Japanese patent publication number 2002-334448 (now patented as U.S. Pat. No. 4,060,546) discloses a method of identifying recording layer information by shifting a starting position of pre-format information in a rotating direction per recording layer.
However, in these methods above, it is necessary that spot light should be focus-controlled and additionally should be track-controlled to a guide groove, therefore there is a time loss. If it is possible to identify a recording layer which is scanned without a tracking control of the recording layer information, high-speed access to the recording layer is achieved.
A main object of the present invention is to obtain identifying information without a tracking control and to achieve high-speed access to a recording layer.